Which neurotransmitter helps control alertness and arousal?

Norepinephrine is a neurotransmitter that plays a crucial role in controlling alertness and arousal. It is part of the body's fight or flight response, primarily affecting the sympathetic nervous system. When norepinephrine is released, it increases heart rate, blood flow to muscles, and glucose release from energy stores, all of which enhance alertness and prepare the body to react to perceived threats. This neurotransmitter is involved in regulating attention, responding to stress, and maintaining wakefulness.

In contrast, some other neurotransmitters listed have different primary functions. Gamma-butyric acid is an inhibitory neurotransmitter that helps to promote relaxation and reduce excitability in the nervous system. Glutamate, while being the main excitatory neurotransmitter, is more associated with cognitive functions like learning and memory rather than specifically controlling arousal. Dopamine is involved in the brain's reward pathways, motivation, and motor control, but it does not primarily regulate alertness and arousal in the same way norepinephrine does.